Mitigation of Arctic permafrost carbon loss through stratospheric aerosol geoengineering

Yating Chen,Aobo Liu,John C Moore

doi:10.1038/s41467-020-16357-8

Abstract

The Arctic is warming far faster than the global average, threatening the release of large amounts of carbon presently stored in frozen permafrost soils. Increasing Earth’s albedo by the injection of sulfate aerosols into the stratosphere has been proposed as a way of offsetting some of the adverse effects of climate change. We examine this hypothesis in respect of permafrost carbon-climate feedbacks using the PInc-PanTher process model driven by seven earth system models running the Geoengineering Model Intercomparison Project (GeoMIP) G4 stratospheric aerosol injection scheme to reduce radiative forcing under the Representative Concentration Pathway (RCP) 4.5 scenario. Permafrost carbon released as CO2 is halved and as CH4 by 40% under G4 compared with RCP4.5. Economic losses avoided solely by the roughly 14 Pg carbon kept in permafrost soils amount to about US$ 8.4 trillion by 2070 compared with RCP4.5, and indigenous habits and lifestyles would be better conserved.

Highlights

The Arctic is warming far faster than the global average, threatening the release of large amounts of carbon presently stored in frozen permafrost soils
We investigate the response of soil C stocks to permafrost million carbonclimate feedback (PCF) in circum-Arctic permafrost region, leveraging the outputs of Earth System Models (ESMs) under two climate projections: RCP4.5 and G4
We note that permafrost C cycle dynamics are poorly represented in CMIP5 models as they were not developed for permafrost soils and do not report vertically resolved soil layers[23]

Summary

Introduction

The Arctic is warming far faster than the global average, threatening the release of large amounts of carbon presently stored in frozen permafrost soils. Instead of directly using the carbon pool or carbon flux outputs of ESMs for analysis, we simulate the large-scale permafrost C response to warming using the PInc-PanTher model[8] modified to include CO2 fertilization effects, forced by the biascorrected soil temperatures (TSL) and net primary productivity (NPP) simulations of 7 ESMs (Methods; Table 1).

Results

Conclusion